Method of using a multi-pass vacuum coating system

1. A method for coating substrates with multiple coating layers, the method comprising:

establishing a sub-atmospheric pressure within a coating system;

transferring each substrate from outside the coating system to inside the coating system though a transfer lock;

moving each substrate through a heating zone prior to entering a coating zone;

traversing the coating zone in a first direction of movement and applying a first coating layer to each substrate in the coating zone using expanding thermal plasma enhanced chemical vapor deposition;

traversing the coating zone a second time and applying a second coating layer to each substrate in the coating zone using expanding thermal plasma enhanced chemical vapor deposition; and

transferring each substrate from inside the coating system to outside the system through the transfer lock; and

purging the heating zone with inert gas when the coating zone is vacant; and

pumping the inert gas out of the coating zone through ports located in the coating zone.

2. The method of claim 1 , wherein the coating system has one coating zone.

3. The method of claim 1 , wherein the step of traversing the coating zone a second time is performed in a second direction of movement, the second direction of movement being different than the first direction of movement.

4. The method of claim 1 , further comprising the step of reversing the direction of movement of the substrates through the system.

5. The method of claim 4 , wherein the reversing step includes receiving and holding a plurality of substrates and then dispensing the substrates in the second direction.

6. The method of claim 1 , wherein multiple substrates are moved through the system simultaneously.

7. The method of claim 1 , further comprising the step of traversing the coating zone more than two times and applying more than two coating layers onto the substrates.

8. The method of claim 7 , wherein the step of traversing the coating zone more than two times includes traversing the coating zone at least one time without applying a corresponding coating to the substrates.

9. The method of claim 8 , wherein the step of traversing the coating zone a second time is performed in a second direction of movement, the second direction of movement being different than the first direction of movement.

10. The method of claim 9 , wherein the second direction of movement is opposite in direction to the first direction of movement.

11. The method of claim 1 , further comprising, prior to coating the substrate, heating each substrate in the heating zone to a temperature suitable for coating.

12. A method for coating substrates with multiple coating layers, comprising:

establishing a sub-atmospheric pressure within a coating system;

transferring each substrate from outside the coating system to inside the coating system though a transfer lock;

heating each substrate in a heating zone before entering a coating zone;

traversing the coating zone in a first direction of movement and applying a first coating layer to each substrate in the coating zone using expanding thermal plasma enhanced chemical vapor deposition;

traversing the coating zone a second time and applying a second coating layer to each substrate in the coating zone using expanding thermal plasma enhanced chemical vapor deposition;

determining if the coating zone is occupied or vacant;

if the coating zone is vacant, purging a heating zone with inert gas; and

pumping the inert gas out of the coating zone through ports located in the coating zone.

13. The method of claim 12 , wherein the coating system has one coating zone.